Design of a high-performance auger spectrometer in the STEM
In high resolution electron beam instruments, Auger analysis is usually performed by keeping the sample in a field free region and employing a standard energy analyzer such as hemispherical sector (HSA) or a cylindrical mirror (CMA). In spite of its simplicity, this arrangement results in long focal length operation and consequently a relatively large spot size. In addition, the collection efficiencies of the energy analyzer coupled with such STEM/SEM/SAM systems tend to be small. If however we perform Auger analysis with the sample immersed in the objective lens field, not only would we have the capability of producing a subnanometer diameter probe, but we can also use the post- or pre-specimen field to parallelize the emitted electrons to yield higher collection efficiency.One approach is to use an electrostatic optics extraction system. In this paper magnetic optics extraction will be considered.